Heating and cooling refrigeration apparatus

ABSTRACT

Refrigerant vapor is passed from a stage, other than the last stage, of a multistage compressor to a condenser. Liquid refrigerant is metered from the condenser to an evaporator or cooler. Refrigerant vapor flow from the cooler to the inlet of the compressor is regulated by control means according to the cooling load. The output of the last stage of the compressor is passed to a second separate condenser containing a tube bundle connected to a heating line. The volume of refrigerant flow to the second condenser is regulated in accordance with the heating demand. Liquid refrigerant is metered from the second condenser to the first condenser. With low-cooling demand and high-heating demand, said first condenser serves as a flash economizer to supply refrigerant vapor to the intake of the last stage of the compressor.

iJnite States Patent Endress et a1.

[54] HEATING AND COOLING REFRIGERATION APPARATUS [73] Assignee: Carrier Corporation, Syracuse, NY.

[22] Filed: July 13, 1970 [211 App]. No.: 54,175

[52] [1.8. CI ..62/117, 62/196, 62/217, 62/510 [51] lint. Cl ..F25b 41/00 [58] Field olSearch ..62/l17,196,510, 159,217, 62/506, 238; 165/62, 63

[56] References Cited UNITED STATES PATENTS 2,888,809 6/1959 Rachtal ..62/217 2,921,446 1/ 1960 Zuliyke ....62/510 3,011,322 12/1961 Tzyzberger ..62/510 3,370,438 2/1968 Hopkinson ..62/196 Primary Examiner'-Meyer Perlin Attorney-Harry G. Martin, Jr. and J. Raymond Curtin [57] ABSTRACT Refrigerant vapor is passed from a stage, other than the last stage, of a multistage compressor to a condenser. Liquid refrigerant is metered from the condenser to an evaporator or cooler. Refrigerant vapor flow from the cooler to the inlet of the compressor is regulated by control means according to the cooling load. The output of the last stage of the compressor is passed to a second separate condenser containing a tube bundle connected to a heating line. The volume of refrigerant flow to the second condenser is regulated in accordance with the heating demand. Liquid refrigerant is metered from the second condenser to the first condenser. With low-cooling demand and high-heating demand, said first condenser serves as a flash economizer to supply refrigerant vapor to the intake of the last stage of the compressor.

7 Claims, 1 Drawing figure PATENTED JANHJ I972 INVENTORS JAMES W. ENDRESS BY ARL M. AND ON H l FRIGIERATION BACKGROUND OF THE INVENTION Air-conditioning systems are in use for providing cooling for a portion of a building and for simultaneously providing heating for another portion of the building. In one such system, refrigeration apparatus, including a refrigerant compressor, a condenser, and a cooler, is employed for handling the cooling load. A separate apparatus including a second compressor and condensing heat exchanger is provided for handling the heating load. In another arrangement which has become conventional, a single compressor is used in conjunction with a double tube bundle condenser system. Water is circulated through one bundle of the condenser and is employed for satisfying the heating load, while the second tube bundle serves in conventional manner to supply liquid refrigerant to the evaporator or cooler for handling the cooling load. In the latter system, employing the double tube bundle condenser, the ratio of hightemperature heating capacity to cooling capacity is not greater than 1 to 2. Accordingly, if there exists a high-heating load simultaneously with a low-cooling load, it is necessary to impose an artificial load on the chilled water cooler or to employ a direct supplement of heat to the hot water heating circuit.

As a result of this limitation, the more conventional heat reclaim systems have typically been found efficient only in large buildings where the internal zone cooling load remains high during the chilly days of early spring and late fall, such systems being unsuitable and uneconomical for smaller installations where the internal zone cooling loads are much smaller in the spring and fall compared to the heating load require ment for the outer zone of the building. Furthermore, yearround power consumption levels are high due to the fact that all the compressor flow is raised to the high-pressure level required for only the heating function.

SUMMARY OF THE INVENTION This invention has as an object apparatus for simultaneously satisfying cooling and heating requirements in an efficient and economical manner. A multistage compressor is employed with the output of one or more stages of the compressor, other than the last stage, supplying refrigerant to a first condenser for providing liquid refrigerant to the cooling load evaporator. The circuit from the evaporator to the intake of the compressor includes conventional flow control means responsive to the cooling load imposed on the evaporator.

The output of the last stage of the compressor is connected to a second separate condenser which serves as a heat exchanger for heating a waterline for satisfying the heating load demand. A liquid refrigerant line extends from the second condenser to the first condenser. The compressor is equipped with flow control means such as a diffuser valve or guide vanes at the last stage of the compressor. Operation of this flow control means is in response to the heating demand imposed on the second condenser.

At low-cooling load demand and high-heating load demand, the first condenser in this arrangement functions as a flash economizer to provide reverse refrigerant vapor flow to provide a sufficient supply of refrigerant vapor for the last stage of the compressor to meet the high heating demand.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic diagram illustrating the arrangement of the apparatus employed in our invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The compressor illustrated in the diagram is of the threestage centrifugal type having impellers 9, 10, and 11. The impellers are rotated by a driver 12 operatively connected thereto. Line 13 extends from the intermediate stage of the compressor to the condenser 14 for the passage of refrigerant vapor thereto. The condenser includes a tube bundle l5 supplied with cooling water from line 16, leaving by return line 17, these lines being connected to a water tower or other source.

Liquid refrigerant formed as the vaporous refrigerant is passed in heat transfer relation with the cooling tower water is conveyed from the condenser M through line 20, metering valve 21, line 23, to evaporator 25 generally referred to in the air-conditioning art as a chiller or cooler. The cooler 25 contains a tube bundle 33 which is connected to the chilled water circuit 35,37.

A refrigerant vapor line 40 extends from the vapor area of the cooler 25 to the inlet of the first stage of the compressor. In conventional fashion, means is provided for controlling the flow of refrigerant vapor from the evaporator to the compresset to vary the capacity of the compressor according to the cooling load demand. Such control means may be in the form of conventional inlet guide vanes, indicated in the diagram at 41, which are controlled by a temperature sensor 43 operatively positioned in the outgoing chilled water line 37. This portion of the apparatus is of conventional arrangement for handling the cooling load of the building.

The last stage of the compressor, indicated by the impeller 11, is connected by refrigerant vapor line 50 to a second separate condenser 51. This condenser contains a tube bundle 53 having an inlet line 55 and a return line 56, lines 55,56 being connected in the hot water heating circuit. Liquid refrigerant formed as heat is extracted therefrom by the water flowing in the hot water heating circuit is conveyed from the second condenser 51 to the first condenser 14 by way of line 57, float operated metering valve 58, and line 60.

The compressor is provided with means operable to control the volume of refrigerant vapor flow from the last stage to the condenser 51. Such control may consist of a diffuser sleeve valve indicated at 60. This valve is movable transversely across the diffuser passage for the control of refrigerant vapor flow from the last stage of the compressor. The diffuser valve 60 is controlled by a temperature sensor 63 attached to the outgoing hot waterline 56. The structural arrangement and operation of such diffuser valve or the equivalent adjustable inlet guide vane arrangement is well known in the art. Such flow control means may be in the form of adjustable inlet guide vanes similar to those shown at All.

If there is a demand for hot water to satisfy a heating load, at a given water chilling condition, the diffuser valve 60 is moved toward open position. The condensing temperature in the hot water condenser 51 increases and accordingly the pressure in the condenser 51. In this situation, part of the flow discharging from the second stage 10 passes on through the third stage 1 l supplying the condenser 51 with hot gas to raise the temperature in the heating circuit 55,56.

If the demand for hot water continues to increase, the third stage diffuser throttle 60 will eventually move to wide open position, at which time all of the flow discharging from the second stage 10 will pass on to the third stage 11 to provide additional hot gas to satisfy the heating demand. At this point, the heating to cooling ratio of approximately 1.2 to l is reached.

The condensed refrigerant will flow from the condenser 51 through lines 57,60 and metering valve 5% to the condenser 14, which then acts as a flash economizer providing refrigerant vapor for reverse flow through the line I3 to the area intermediate the second and third stages of the compressor.

If the lines 16,17 of condenser M are connected to an outdoor cooling tower, the flow of condensing water may be restricted or turned off to maintain a sufficiently elevated temperature in condenser 14 for the provision of sufficient refrigerant vapor in reverse flow to the last compressor stage to permit impeller l l to meet the high-lift condition necessary to handle the high-heating load imposed on the condenser 51.

It will be understood by those knowledgeable in the art that the flow of gas through the centrifugal compressor cannot be reduced to zero. To avoid such a situation, the inlet guide vanes 41 and the difi'user valve 60 are rigged so that they do not fully close. Accordingly, if there is no heating load, as for example, during the warm season and the heating line connected to the pipes 55,56 is closed off, the nominal flow of gas through the third stage 11 does not condense in the condenser 51, and the float valve 58 will be closed. To prevent overheating of the third stage 11, a branch circuit 65 may be arranged in shunt with the float valve 58. This circuit includes an orifice 67 dimensioned to pass a sufficient flow of refrigerant vapor to the condenser 14 to prevent the overheating of the third stage impeller. An alternate arrangement is to open valve 75 so that sufficient flow passes through the third stage to prevent overheating. Valve 77 may be left open or closed.

As previously stated, the inlet guide vanes do not close to an extent as to be likely to create a surge situation in the compressor. Accordingly, at high-heating demand, there is a flow of refrigerant vapor through the stages 9 and 10 of the compressor to provide adequate flow of refrigerant vapor to the condenser 51 to meet a high-heating demand. The transfer of refrigerant vapor and/or liquid refrigerant from the condenser 51 to the condenser 14 presents no problem in that the cooler will have imposed upon it some cooling load determined by the sensor 43. Also, at this point the condenser 14 acts as a flash economizer, and reverse flow of refrigerant vapor takes place in line 13 as indicated by the arrow 70. It is believed to be apparent that with the arrangement or apparatus, the compressor is capable of accommodating a high-heating demand during a low-cooling demand imposed on evaporator 25.

In addition to the apparatus having the capability of having high-temperature heating capacity relative to cooling capacity, it also will function to handle a cooling load in excess of design capacity. A branch line 73 is connected between the lines 13 and 50 and includes a flow-control valve 75. A valve 77 may be arranged in the line 50 downstream from the branch line 73. A valve 78 is connected in line 13 intermediate the compressor and branch line 73. Ifthere is an excessive rise in ambient temperature, valve 78 is closed; valve 77, if furnished, may be closed; and valve 75 is opened. The diffuser sleeve valve 60 may also be manually moved to wide open position. In this situation, the output of all three stages of the compressor is passed to the condenser 14 to increase the supply of liquid refrigerant through line 20, metering valve 21, and line 23 to the cooler 25 to increase the capacity thereof to satisfy the cooling demand then exceeding the design capacity of the machine. In handling the excessive cooling load in the manner set forth, the required high-lift temperature is obtained in condenser 14 automatically if cooling tower water is supplied to the lines 16,17. This, inasmuch as the temperature of the cooling tower water will be increased by the high outdoor temperature. If condenser 14 is furnished with cooling water from a different source as, for example, from a well, at a relatively uniform temperature, the flow through the lines 16,17 may be reduced by flow control valves in the conventional manner. in the prior system referred to employing the double tube bundle single condenser, such arrangement is incapable of producing a ratio of high-temperature heating to cooling any greater than 1 to 2. With the apparatus arrangement of our invention, a greater increase in heating to cooling capability is provided, achieving a ratio of approximately 1.2 to l. The heating-cooling apparatus of our invention is particularly suitable and more efficient for smaller installations where the internal zone cooling loads are much smaller in the spring and fall seasons.

The centrifugal-type compressor is particularly well adapted for our system in that the diffuser valve 60 under the control of the sensor 63 effects efficient volume control of refrigerant vapor to the heating condenser 51 in accordance with the heating load imposed thereon. Also, the inlet guide vane control All functions particularly well in the combined cooling and heating system.

We claim: 1. Apparatus for simultaneously satisfying heating and cooling demands in a building comprising a multistage compressor, a condenser, and a cooling load cooler connected to form a circuit including first flow passage means for the flow of refrigerant vapor from a stage of said compressor, other than the last stage, to said condenser and said passage including means for controlling liquid refrigerant flow from said condenser to said evaporator, capacity control means regulating the flow of refrigerant vapor from said cooler to the inlet of said compressor in accordance with the cooling demand imposed on said cooler, at second condenser, second flow passage means for passing refrigerant vapor from the last stage of said compressor to said second condenser, means for circulating water to be heated for heating load demand in heat exchange relation to the refrigerant in said second condenser, refrigerant flow control means for regulating the flow of refrigerant vapor from said last compressor stage to said second condenser in accordance with the heat demand load imposed thereon, and a liquid refrigerant line including flow control means extending from said second condenser to said first condenser.

2. Apparatus as set forth in claim 1 wherein said compremor includes first, second, and third stages, said first flow passage means extending from said second stage to said first condenser.

3. Apparatus as set forth in claim 1 wherein said refrigerant flow control means for regulating the flow of refrigerant vapor from said last stage of said compressor includes a diffuser valve operable in response to the temperature of the heating water leaving said second condenser.

4. Apparatus as set forth in claim 1 wherein said flow control means in said liquid refrigerant line extending from said second condenser to said first condenser includes a float operated metering valve.

5. Apparatus as set forth in claim 1 wherein said liquid refrigerant line extending from said second condenser to said first condenser includes a float operated metering valve, a branch line connected in said refrigerant line in shunt with said metering valve, said branch line including an orifice member.

6. Apparatus as set forth in claim 1 including a branch passage line connecting said first and second flow passage means, a flow control valve connected in said branch line, a flow control valve connected in said first flow passage means intermediate said compressor and said branch line, said flow control valves being operable to direct the flow of refrigerant vapor from said last stage of said compressor to said first condenser.

7. The method of simultaneously providing heating and cooling for areas of a building having heating and cooling circuits consisting of discharging refrigerant vapor from an intermediate stage of a multistage compressor to a condenser passing liquid refrigerant from the condenser to a cooler connected to the cooling circuit, regulating the flow of refrigerant vapor from said cooler to the inlet of the compressor according to the cooling load demand on the cooling circuit, passing a volume of refrigerant vapor from the last stage of the compressor to a heat exchanger connected to the heating circuit in proportion to the heating load demand on said heating circuit, and passing liquid refrigerant from said heat exchanger to said condenser.

19! i l i 

1. Apparatus for simultaneously satisfying heating and cooling demands in a building comprising a multistage compressor, a condenser, and a cooling load cooler connected to form a circuit including first flow passage means for the flow of refrigerant vapor from a stage of said compressor, other than the last stage, to said condenser and said passage including means for controlling liquid refrigerant flow from said condenser to said evaporator, capacity control means regulating the flow of refrigerant vapor from said cooler to the inlet of said compressor in accordance with the cooling demand imposed on said cooler, a second condenser, second flow passage means for passing refrigerant vapor from the last stage of said compressor to said second condenser, means for circulating water to be heated for heating load demand in heat exchange relation to the refrigerant in said second condenser, refrigerant flow control means for regulating the flow of refrigerant vapor from said last compressor stage to said second condenser in accordance with the heat demand load imposed thereon, and a liquid refrigerant line including flow control means extending from said second condenser to said first condenser.
 2. Apparatus as set forth in claim 1 wherein said compressor includes first, second, and third stages, said first flow passage means extending from said second stage to said first condenser.
 3. Apparatus as set forth in claim 1 wherein said refrigerant flow control means for regulating the flow of refrigerant vapor from said last stage of said compressor includes a diffuser valve operable in response to the temperature of the heating water leaving said second condenser.
 4. Apparatus as set forth in claim 1 wherein said flow control means in said liquid refrigerant line extending from said second condenser to said first condenser includes a float operated metering valve.
 5. Apparatus as set forth in claim 1 wherein said liquid refrigerant line extending from said second condenser to said first condenser includes a float operated metering valve, a branch line connected in said refrigerant line in shunt with said metering valve, said branch line including an orifice member.
 6. Apparatus as set forth in claim 1 including a branch passage line connecting said first and second flow passage means, a flow control valve connected in said branch line, a flow control valve connected in said first flow passage means intermediate said compressor and said branch line, said flow control valves being operable to direct the flow of refrigerant vapor from said last stage of said compressor to said first condenser.
 7. The method of simultaneously providing heating and cooling for areas of a building having heating and cooling circuits consisting of discharging refrigerant vapor from an intermediate stage of a multistage compressor to a condenser passing liquid refrigerant from the condenser to a cooler connected to the cooling circuit, regulating the flow of refrigerant vapor from said cooler to the inlet of the compressor according to the cooling load demand on the cooling circuit, passing a volume of refrigerant vapor from the last stage of the compressor to a heat exchanger connected to the heating circuit in proportion to the heating load demand on said heating circuit, and passing liquid refrigerant from said heat exchanger to said condenser. 